1. Field of the Invention
The subject invention is directed to surgical implants, and more particularly, to a percutaneous interspinous process implant and fusion device.
2. Description of Related Art
The spine consists of a column of twenty-four vertebrae that extend from the skull to the hips. Discs of soft tissue are disposed between adjacent vertebrae. In addition, the spine encloses and protects the spinal cord, defining a bony channel around the spinal cord, called the spinal canal. There is normally a space between the spinal cord and the borders of the spinal canal so that the spinal cord and the nerves associated therewith are not pinched.
Over time, the ligaments and bone that surround the spinal canal can thicken and harden, resulting in a narrowing of the spinal canal and compression of the spinal cord or nerve roots. This condition is called spinal stenosis, which results in pain and numbness in the back and legs, weakness and/or a loss of balance. These symptoms often increase after walking or standing for a period of time.
There are number of non-surgical treatments for spinal stenosis. These include non-steroidal anti-inflammatory drugs to reduce the swelling and pain, and corticosteroid injections to reduce swelling and treat acute pain. While some patients may experience relief from symptoms of spinal stenosis with such treatments, many do not, and thus turn to surgical treatment. The most common surgical procedure for treating spinal stenosis is decompressive laminectomy, which involves removal of parts of the vertebrae. The goal of the procedure is to relieve pressure on the spinal cord and nerves by increasing the area of the spinal canal.
Interspinous process decompression (IPD) is a less invasive surgical procedure for treating spinal stenosis. With IPD surgery, there is no removal of bone or soft tissue. Instead, an implant or spacer device is positioned behind the spinal cord or nerves between the interspinous processes that protrude from the vertebrae in the lower back. A well-known implant used for performing IPD surgery is described in U.S. Pat. No. 6,419,676, the disclosure of which is herein incorporated by reference in its entirety. However, implantation and deployment of this prior art device still requires an incision to access the spinal column.
An interspinous process implant placed in a minimally invasive surgical procedure is disclosed in U.S. Patent Application Publication 2008/0243250, which is also incorporated herein by reference in its entirety. This implant functions as a spacer between two adjacent spinous processes, but it is not designed to stabilize the spinous process and can migrate over time.
It would be advantageous to provide an implant for performing IPD procedures that can be percutaneously inserted into the interspinous process space to effectively treat lumbar spinal stenosis by distracting, or maintaining distraction, and sufficiently stabilizing adjacent spinous processes, and thus, adjacent vertebrae. The interspinous process implant of the subject invention, achieves those objectives.